In this study, high manganese steel specimens were machined with graphite electrode and various processing parameters by electro erosion method. It is a known fact that the craters generated by the EDM have a notch effect on the fatigue life. Therefore, Rz and Sm roughness parameters are calculated as the roughness maximum crater depth and width, respectively, and the theoretical fatigue life calculations are performed on the treated surfaces. In the processes, the tool polarization was also changed and the measured roughness values were higher in the positive polarity, so that the fatigue limit life was reduced in the calculations made with the area(1/2) model. In EDM, when using a graphite electrode, in the case of reverse polarity machining, the surface roughness has an effect on increasing the fatigue life.